Vehicle Safety Systems
601 N.W. 25th Avenue
Ocala, FL 34475
Dear Mr. Roberts:
This responds to your letter of April 21, 1997, concerning a seat belt system you have designed. You asked us to evaluate whether the design would comply with S188.8.131.52 of Standard No. 208.
By way of background information, the National Highway Traffic Safety Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under 49 U.S.C. chapter 301, it is the responsibility of the manufacturer to ensure that its vehicles or equipment comply with all applicable standards. The opinion provided below is based on the facts provided in your letter.
As described in your letter, the seat belt assembly at issue is a Type 2 assembly intended for use in forward-facing rear seats in conversion vans. The lower end of the belt is attached to the vehicle floor and the upper end is attached to a retractor mounted on the roof support. The belt itself is fed through a crescent shaped slot in a mounting plate fixed to the roof rail. This crescent shaped slot allows the belt to assume different positions relative to a seat occupant depending on the height at which the belt is latched when fastened. The arc described by the crescent shaped slot is "preferably at least 5 cm longer than the width of the webbing."
Standard No. 208 was amended in a final rule published on
August 3, 1994, (59 FR 39472) to improve the fit and increase the comfort of safety belts for a variety of different sized occupants. S184.108.40.206 of Standard 208 reads as follows:
As an alternative to meeting the requirement of S7.1.2, a Type 2 seat belt assembly shall provide a means of automatically moving the webbing in relation to either the upper anchorage, or the lower anchorage nearest the intersection of the torso belt and the lap belt. The distance between the midpoint of the webbing at the contact point of the webbing and the anchorage at the extreme adjustment positions shall be not less than five centimeters, measured linearly.
According to your letter, the crescent-shaped slot located in the guide plate near the upper anchorage automatically moves the webbing in relation to the upper anchorage when the belt is latched around different sized users. This guide plate, which attaches to vehicle structure at the roof rail, is also an anchorage. S3 of Standard No. 210, Seat Belt Assembly Anchorages, defines a seat belt anchorage as "...any component, other than the webbing or straps, involved in transferring seat belt loads to the vehicle structure, including, but not limited to, attachment hardware ..."
If the distance, measured linearly, between the midpoint of the webbing at the contact point with the guide plate at the extreme adjustment positions is greater than five centimeters, it appears that your design would meet the requirement of S220.127.116.11. However, as an alternative means of providing the adjustment specified in S7.1.2, S18.104.22.168 requires that a Type 2 assembly shall provide a means of automatically moving the webbing in relation to the upper anchorage or the lower anchorage nearest the intersection of the torso and lap belts. If, in operation, the system you have designed does not automatically move the webbing in relation to the upper anchorage to accommodate occupants, the system you have designed would not meet S22.214.171.124. I note, however, that NHTSA is not able to make such a determination from looking at your drawings. Any determination of compliance would require testing of the system as installed in a vehicle.
NHTSA compliance testing has also revealed that guide plates, d-rings and other guiding devices can tear or sever webbing under the severe loads experienced in an impact. The guide plates incorporated in your design should therefore be constructed in a fashion which will minimize this risk.
You should also be aware that under 49 U.S.C. 30118-30122, each motor vehicle manufacturer must ensure that its vehicles are free of safety-related defects. If NHTSA or the manufacturer of a vehicle determines that the vehicle contains a safety-related defect, the manufacturer must notify purchasers of the defective vehicle and remedy the problem free of charge. Compliance with applicable standards does not relieve the manufacturer of responsibility in the event a defect exists.
I hope this information has been helpful. If you have any other questions, please contact Otto Matheke of my staff at this address or by phone at (202) 366-5253.
Acting Chief Counsel